Implemented: Url link shorten handler plugin system

This system of url link shorten handlers is ini setting configurable and enabled via workflow edit view option.

Handlers tested and supported by default out of the box:
- is.gd
- to.ly
- v.gd
- tinyurl.com
- goo.gl
- bit.ly
- ow.ly

The default link shortening service is: is.gd. We support this by default because it does not require an api key to use the service. 

Also worth noting we were going to default to to.ly as suggested by @L0rdJ but during testing the service went offline for longer than 10min (not a good sign of reliability for a service) also when we found their network status page in google cache, http://stats.to.ly the page shows they have a whole lot of downtime regularly (sometimes for hours) all this led us to choose a more reliable service to use as the default.

The link shortening workflow option is disabled by default. This is important because some services like linkedin or twitter have their own url shortening services built-in that shorten urls in messages on the fly and as such may not need another service (we found this out after development during testing). Still some prefer to use their favorite 3rd party url shortening services regardless (some like bit.ly for their statistics tracking and other features).

Link shortening services goo.gl, bit.ly and ow.ly all require an api key which must be configured in a settings override of settings/nxcsocialnetworks.ini.append.php and ini caches cleared. These services have all been tested and work the same as the rest.

Please let us know what you think!

Cheers,
Brookins Consulting